Crooked Harbour earns its English name from the irregular shape of the water body, pinched and curved by the islands and peninsulas that frame it. The harbour is enclosed primarily by Crooked Island — Kat O in Cantonese — and the smaller island of Ap Chau to the northeast, with the mainland New Territories forming the southern and western shores. Beyond the harbour's northern opening lies Double Haven, and beyond that, the broader expanse of Mirs Bay. The islands within and around the harbour form a miniature archipelago: Ap Chau and its cluster of attendant islets, Fun Chau, Siu Nim Chau, Tai Nim Chau, Lo Chi Pai, and others. Each one is distinct — different shapes, different histories, different relationships to the water around them.

The rocky shores of Crooked Harbour display a feature geologists find unusual: wave-cut benches, flat ledges six to ten metres wide, cut horizontally into the rock along sediment layers exposed at the waterline. These benches form where the sea erodes softer rock between more resistant strata, producing a staircase effect at the base of the cliffs that is uncommon elsewhere in Hong Kong's coastline. The same feature appears at nearby Ping Chau. The rocks here are sedimentary — laid down in ancient shallow seas and later compressed and uplifted — and their layered structure makes them particularly susceptible to this kind of patterned erosion. Walking the foreshore at low tide, you can read the geology directly in the rock beneath your feet.

Beneath the surface of the harbour, the ecology is equally distinctive. Eelgrasses were discovered at Lai Chi Wo — a village on the mainland shore of the harbour — in 1977, and the Agricultural and Fisheries Department of the Hong Kong government moved to protect them. These submerged meadows provide habitat and nursery grounds for the harbour's marine life, filtering the water and stabilizing the seabed. Among the residents of the eelgrass beds is Periclimenes demani, a small and translucent shrimp that depends on the grass for shelter. The protected status of the eelgrass reflects the broader ecological sensitivity of the Crooked Harbour area, which lies adjacent to the Lai Chi Wo Special Area and the Double Haven conservation zone.

What makes Crooked Harbour feel singular is the contrast it embodies. From the water, the Shenzhen skyline is visible to the north — the towers and container infrastructure of one of China's largest cities rising just beyond the border. The harbour itself remains quiet, its islands largely undeveloped, its waters still fished by small boats in traditional fashion. The restricted zone status of the Sha Tau Kok area on the mainland shore has helped preserve that quiet: access requires permits, and the bureaucratic barrier has, inadvertently, kept the kind of mass tourism that transforms coastal Hong Kong at bay. Crooked Harbour sits close to one of the most intensely developed urban corridors on earth, and yet it looks, at times, like it belongs to a much earlier century.